Determining the Antiquity of Dog Origins: Canine domestication as a model for the consilience between molecular genetics and archaeology, by MICHELLE J RAISOR
The note, ‘About the Author’ at the front of this publication describes Michelle Raisor as a person of many and varied accomplishments. Besides a B.Sc in recreation and parks from Texas A & M University, she has an MA in Anthropology, and she has worked as a research associate in a number of different molecular genetics laboratories. Raisor was also a research associate in a department of veterinary medicine, and she has a life-long passion for dogs, so she is well qualified to enter the fray on where, when, and from what was the dog first domesticated.
There are six sections to Determining the Antiquity of Dog Origins, a long chapter on the basics of molecular genetics follows a short introduction. This is followed by a chapter on the behaviour of wolves, followed by another long chapter on the archaeological record, which is mainly concerned with the fossil and subfossil remains of canids. This is followed by a discussion and conclusion.
The collaboration, or what Raisor calls ‘consilience’, between molecular geneticists and archaeologists and archaeozoologists has only proliferated relatively recently and it gives me a great feeling of déjà vu for the beginnings of radiocarbon dating, which in the 1950s and 60s grew from what seems to me to be very much the same sort of collaboration, but between physicists and archaeologists. What is so similar about molecular genetics and radiocarbon dating when applied to archaeology is that the researchers on each side know so little about the science of the other, and so each has to take what the other says on trust. This has led to the publication of some extraordinary errors, for example in the dating of the dog remains from Jaguar Cave in Idaho that were first dated to c. 10,370 BP (making them the acclaimed, earliest dogs in North America), but later the bones were directly dated to c. 3200±80 BP and 940±80 BP. And in mtDNA analysis, the best known recent example is the misinterpretation of the molecular evidence published by Vilà et al. in their Science paper of 1997, in which they stated that the split between the wolf and the dog occurred c. 135,000 years ago. It is now considered that Vilà et al., in arriving at this date, did not take into due account the probable errors in their estimates, particularly in the calibration point between the outgroup and the wild ancestor, ie the one million years that was taken as the time of split of an ancestral canid into the separate species of coyote and wolf (see Dobney & Larson, in press).
Molecular geneticists and archaeozoologists are beginning to appreciate much the same sort of difficulties about each other’s research as radiocarbon physicists and archaeologists did some forty years ago. They realize that great caution needs to be placed on the interpretation of evidence from both sides, but it seems that Michelle Raisor has no qualms about entering both fields and publishing her views and interpretation of mitochondrial inheritance, mapping the canine genome, evolution, the process of domestication, behavioural patterns of wolves and dogs, osteological differences between wolves and dogs, and lists of the worldwide sites from where early dog remains have been recovered. In many ways this makes her book a useful review of the present status of evidence on the origins and antiquity of the domestic dog and it has a commendable bibliography, but regretfully no index. However, Raisor has a bias in her thinking about the evolution of the domestic dog that I have commonly heard from dog breeders, but never from biologists, and that is that the wolf could not be the direct progenitor of the dog because there are too many differences in their behaviour.
I am an archaeozoologist and I have no more knowledge of the technology of genetics than I have of radiocarbon dating, so I am not qualified to comment on Raisor’s description of the ‘Basics of molecular genetics’, but I wonder whether she gave this section to a geneticist for review before submitting it for publication? There are no acknowledgements in the book and regretfully it is clear that the text received no copyediting, for there are many typos and errors of grammar and style.
Raisor goes wrong in arguing at length against various theories about the domestication process, which as far as I know, no scientist has ever put forward, such as, ‘what would the advantage be for early man to bring a dangerous carnivore into its camp and condition it to have no fear of humans?’ And again, no archaeozoologist would admit to holding the simplistic view that, as early as 15,000-135,000 years ago, humans would or could have intentionally captured, tamed or controlled wild wolves, and then selectively bred them to produce dogs. Raisor states that it is because of her disbelief in this theory that she supports an alternative hypothesis of canine domestication. Although her reasoning is difficult to follow, it seems she ends up with a theory for the process of domestication of the dog, which does not differ widely from that of mainstream archaeozoology. Raisor first accepts that the changes in the mtDNA between wolves and dogs that were recorded by Vilà et al. could indicate that a separation occurred 135,000 years ago, but she suggests these changes were a result of natural evolution in a changing environment and had nothing to do with human intervention (p. 84). On p. 86 it transpires that she sees this changed environment not as the natural world but as the surroundings of human camps where the canids that were transitional between wolves and dogs scavenged. Then, ‘at approximately 15,000 years ago, some dogs had sufficiently evolved that some especially adaptive animals could be assimilated into human culture.’ This seems to me to be a reasonable hypothesis, except that its early beginnings at 135,000 years ago are now discounted, and she doesn’t mention the salient point that in order for changes in the genetic constitution of an organism to be inherited, and thereby to evolve into a new form, there has to be reproductive isolation from its ancestral population.
In this review, Michelle Raisor has shown herself to be a pioneer in consilience (defined in the Oxford Dictionary as ‘jumping together’), between molecular genetics and archaeozoology. Clearly, reviews of this kind will be of great value for the future of both disciplines, but it is essential that they should be written by a scientist with a real understanding of the strengths and weaknesses of the methodology together with an archaeozoologist who can critically assess the results, rather than taking them at face value and then constructing hypotheses to fit them. It is also essential that both sides should be expertly refereed before agreement on publication is reached.
Review Submitted: September 2005
The views expressed in
this review are not necessarily those of the Society or the Reviews
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